Communications systems, such as multi-tone links, often perform signal processing operations on data based on a communications technique being used and/or one or more characteristics of a communications channel. For example, communication systems may code and/or frequency band limit the data using a transformation, such as a discrete Fourier transform (DFT) or an inverse discrete Fourier transform (IDFT). Filters, such a finite impulse response (FIR) filter or a polyphase filter, may equalize and/or shape a spectral content of the data in at least a band of frequencies corresponding to at least one communications channel. And depending on the characteristics of the communications channel, the filters and/or a modulation code used to modulate the data may also be adapted.
In some communications systems it is advantageous to implement many of these signal processing operations in a transmitter. However, supporting a wide variety of operations in the transmitter, especially in those systems that include adaptive signal processing and/or adaptive modulation coding, may increase complexity and/or expense. There is a need, therefore, for an improved digital transmitter in communication systems.
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